Dispersion bandwidth deduced from coherency of wave recordings from spatially separated sites

Abstract

In an earlier paper it was pointed out that temporal variability in the dispersive properties of the propagation medium can cause a band of wave velocities to be associated with each frequency component in the time series of a sampled quantity. This results in degrading the coherence between stations separated in the direction of propagation and can cause significant error in the apparent wave velocity as deduced from the phase of the cross spectra. This bandwidth is complementary to the concept of beamwidth, which principally degrades the coherence between stations separated perpendicular to the direction of propagation. The present paper uses numerical procedures to extend the earlier results to larger beamwidths and bandwidths.